Liquid pump



FIG. 1 is a front elevational view of a liquid pump showing the new design;

FIG. 2 is a side elevational view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a rear elevational view thereof; and,

FIG. 5 is a bottom plan view thereof.

The broken lines in the drawings depict environmental subject matter only and form no part of the claimed design. 

I claim the ornamental design for a liquid pump, as shown and described. 